NZ Weather Forum

MetService May 2022 Brief Summary - In like a lion, out like a lamb

High pressure dominated across Aotearoa New Zealand for the first half of May, with most regions experiencing unusually dry and sunny weather through mid-month. Soil moisture deficits steadily increased (apart from eastern North Island), with a medium-scale drought event declared across Waikato and south Auckland on 16 May.

A major pattern shift occurred shortly thereafter, with a generally unsettled and stormy weather pattern observed across the second half of May. A cold front brought the first glimpse of winter-like weather from the 20th May, with a cold snap bringing snow to relatively low levels across the far south, and the South Island snow fields saw their first decent snowfall of the season.

An active Southern Ocean remained fired up through the third week of the month, bringing stormy, squally and thundery westerlies. The final week of May saw activity shift northwards, with deep Tasman lows bringing warm northerly gales and bouts of heavy rain (rain rates exceeding 40 mm/hour were recorded at Whitianga, Whakatane and Great Barrier Island) across the North Island.

Most regions saw measurable rainfall in the last fortnight of May, and the active weather pattern looks set to continue well into June 2022.

May 2022 Average Temps, Rainfall, Sunshine and departures from 1981-2010 normals ℅ NIWA

Site                     T-max °C      T-min °C       T-mean °C     Rain mm      Sun hrs

Auckland, Mangere       19.4  +1.9    10.9  +0.5    15.1  +1.1     69   66%    174  121%
Tauranga Aero           19.0  +1.7    10.6  +1.3    14.8  +1.5    151  137%    n/a   n/a
Hamilton Aero *         18.7  +1.9     6.5  +0.1    12.6  +1.0    180  168%    176  122%
Wellington, Kelburn     16.0  +1.7    10.8  +1.8    13.4  +1.7     98   88%    111   84%
Christchurch Aero       16.6  +2.3     4.8  +1.1    10.7  +1.7     50   86%    170  121%
Dunedin, Musselburgh    15.4  +2.7     7.6  +1.7    11.5  +2.2     25   39%    129  118%
Greymouth Aero          16.7  +2.2     9.6  +2.5    13.2  +2.4    374  189%    114  111%
* Sunshine from Ruakura